I've looked around and two boards stick out to me as the best ( but not too expensive ) motherboards for your i5 4670k and these are :
1) Asus Z87M-PLUS Intel Z87 (Socket 1150) DDR3 Micro ATX Motherboard
http://www.aria.co.uk/Products/Components/Motherboards/Intel Socket/Socket 1150 - Intel Z87/Asus Z87M-PLUS Intel Z87 %28Socket 1150%29 DDR3 Micro ATX Motherboard ?productId=56875
.. one of the best sub £100 all round motherboards for the socket 1150 designation... and although it only supports crossfire the remaining features such as usb3.0 and sata 6gb are a must .. it also has some interesting overclocking features such as overclocking protection ( ASUS 5X PROTECTION and ASUS ESD Guards )
2) MSI Z87-G45 GAMING Intel Z87 (Socket 1150) ATX Motherboard
http://www.aria.co.uk/Products/Components/Motherboards/Intel Socket/Socket 1150 - Intel Z87/MSI Z87-G45 GAMING Intel Z87 %28Socket 1150%29 ATX Motherboard ?productId=55798
... theres no doubt that this motherboard is in a league of its own and all for just £117... theres both sli and crossfire support and the board will be a showstopper in any case,especially with a side window..... theres also a killer nic network adapter which is a must for online gamers ( since it reduces ping times and also prioritises network traffic )both these motherboards would be a excellent choice
... however on this occasion I have to recommend the MSI Z87-G45 GAMING Intel Z87 (Socket 1150) ATX Motherboard due to its superior features ( which also include OC Genie 4 for 1 click overclocking ) ....
I hope this helps
Source- Yahoo Answers